(1) Field of the Invention
The present invention relates to the analysis of compounds, particularly, although not exclusively chemical compounds utilised in the healthcare, pharmaceutical, cosmetic and environmental sectors.
(2) Description of the Art
It has become the case that in the search for ever more effective pharmaceutical compounds an ever-increasing amount of time, effort and resources have been devoted to identifying and isolating potentially beneficial chemical compounds. Traditionally, the approach has been to select a molecular target within a biochemical pathway, such as an enzyme or a receptor where interaction with the target by a compound could lead to changes which treat the disease. Typically, the interaction would take the form of the compound inhibiting or exciting the pathway. Clearly, a large number of targets will be under investigation at any one time. In order to evaluate the target against potentially useful compounds it is necessary to produce samples of the target for testing, typically through a cloning process. The target is then screened in a series of tests against these compounds with a view to eliminating those compounds which are unsuitable and to identify those compounds that are potentially valuable. It is sometimes the case that there may be sufficient biostructural information on the molecular target to suggest the design of potentially valuable compounds. Even so, for the most part hundreds of thousands of compounds are typically screened using robotic technology. Typically, the entire process from initial selection of a target through to the identification of candidate compounds can take several years.
Once identified as potentially of value in this first screening phase, compounds showing the appropriate activity are subjected to further screens with the aim of determining their level of potency and selectivity for the target. From these data, leads will be identified.
Once a potential candidate compound has been identified, it is then subjected to further development including more screening to meet the needs of various studies both clinical and non-clinical studies. The biological effects of a compound will be assessed, wherever possible avoiding using animals in safety testing. Thus, cells in culture are an attractive alternative for the basis for such investigations. Increasingly automation is being applied to such assessment and whilst for the most part conventional assaying techniques are utilised there has been some initial attempts at employing automated techniques.
One such technique which has been applied to the analysis of cell culture in response to a compound is that set out in U.S. Pat. No. 6,377,057 which describes a technique and apparatus for classifying biological agents according to the spectral density signature of evoked changes in cellular electric potential. It is suggested in the Patent that the approaches it teaches are intended to go beyond those previous attempts to measure cellular electric potential. Such early attempts have, it is suggested, produced output more suited to interpretation by an experienced neuroscientist. Indeed, although such tools have been available to researchers and expert practitioners such as cardiologists since the early 1970's, it is suggested that the invention disclosed in the Patent is intended to be of more general use. As such the patent discloses a relatively unsophisticated analysis mechanism based on interpreting the power spectral density (PSD) of a cellular response. Thus, whilst the Patent teaches that the technique is capable of identifying unknown compounds and determining the characteristics of compounds, analysis based purely on the spectral density changes of such evoked membrane potential or action potential is considered to limit the value of the results obtained in the interests of reducing the complexity of analysis.